I am a relatively skinny guy. I am 6' 170 and i have well defined arms. When i flex i can see all those striations in my shoulders and veins in my biceps etc etc. But my abs are not showing.When i flex i can see the top two but not much more. I try to grab extra fat on y stomach buy cant. So whats goin on...do i have underdevleoped abs or still more fat to lose in order to have a nice perfect six pack.